uv (and direnv)

These instructions install uv and direnv in your home directory.

• uv is a very fast and powerful Python installer, package manager and virtual environment manager written in Rust.
• direnv is a shell extensions that automatically loads or unloads environment variables when you enter or leave a directory. This allows you to activate or deactivate a Python virtual environment when entering or leaving a directory.

In this tutorial, you’ll use uv to create a virtual environment with a specific Python version, and install the numpy package.

Install uv

Install uv in your $HOME/.local/:

curl -LsSf https://astral.sh/uv/install.sh | sh

Ensure that $HOME/.local/bin is included in your PATH (e.g. .bashrc).

Install direnv

Install direnv in your $HOME/.local/:

curl -sfL https://direnv.net/install.sh | bash

Add the following line to your shell startup file (e.g. ~/.bashrc):

eval "$(direnv hook bash)"

Reload your shell afterward, or manually execute this line in your current shell.

Setup a Python Virtual Environment

The following instructions give some ideas on how to use uv.

• create a directory numpy_project and set the python version in the virtual environment to 3.14:

uv init numpy_project --python 3.14

• in the directory numpy_project create the virtual environment:

cd numpy_project
uv venv

• enable the automatic activation of the virtual environment with direnv:

echo "source .venv/bin/activate" > .envrc
direnv allow

• add numpy to the virtual environment:

uv add numpy

• test the setup:

python --version
python -c "import numpy; print(numpy.__version__)"

That’s all folks!